Cross-Linked Cellulosic Fiber Tissue for Bulk Without Strength Loss
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Solution Overview
Problem
Existing paper products face challenges in balancing bulk, strength, and softness, often resulting in unacceptable levels of lint and slough, which are inversely proportional to tensile strength, making it difficult to produce a tissue product that meets user standards.
Innovation Solution
The use of cross-linked fibers, specifically hardwood kraft fibers treated with agents like 1,3-dimethyl-4,5-dihydroxy-2-imidazolidinone, in a multi-layered tissue web structure, where cross-linked fibers are selectively incorporated into layers to increase bulk and reduce stiffness without compromising tensile strength, is employed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If embossing is used to increase bulk, then bulk is improved, but sheet stiffness increases and softness decreases
Solution Approach 1:
The patent applies chemical treatment to fibers to change their physical parameters, specifically using cross-linking agents or surfactants to modify fiber surface properties and inter-fiber bonding characteristics, thereby achieving bulk increase without the mechanical deformation that causes stiffness
Solution Approach 2:
The patent introduces chemical substances as intermediaries between fibers to control bonding behavior. These agents mediate the interaction between fibers, allowing bulk enhancement through controlled debonding or surface modification without requiring mechanical embossing that would increase stiffness
2Volume of stationary object
If fiber-fiber hydrogen bonding is reduced to increase bulk, then bulk is improved, but tensile strength decreases
Solution Approach 1:
The patent changes the chemical parameters of fiber surface interaction by introducing cross-linking agents that create covalent bonds or strong secondary bonding, replacing or supplementing hydrogen bonds with stronger bonding mechanisms that maintain tensile strength while allowing bulk enhancement
Solution Approach 2:
The patent creates a composite fiber structure where treated and untreated fibers are combined, or where multiple types of bonding mechanisms (hydrogen bonds, covalent cross-links, mechanical interlocking) work together to provide both bulk and tensile strength simultaneously
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in tissue products with improved bulk, reduced stiffness, and maintained strength, while minimizing lint and slough, thereby achieving a balance of properties that satisfy user expectations.
Implementation Method 1
reacting wood pulp fibers with cellulose reactive agents, such as triazines, to alter the degree of hydrogen bonding between fibers
Implementation Method 2
sufficient interfiber bonds are broken at the outer tissue surface to provide a plethora of free fiber ends on the tissue surface
Implementation Method 3
The cationic quaternary ammonium entity allows for the material to be retained on the cellulose via ionic bonding to anionic groups on the cellulose fibers
Implementation Method 4
The long chain alkyl groups provide softness to the tissue sheet by disrupting fiber-to-fiber hydrogen bonds in the sheet
Data Source
AI summary
The disclosure provides tissue webs and products comprising cross-linked cellulosic fibers. In certain embodiments cross-linked cellulosic fibers are selectively disposed in one or more layers of a multi-layered tissue, wherein the tissue layer comprising cross-linked fibers is adjacent to a layer which is substantially free from cross-linked fiber. The cross-linked fibers may include hardwood kraft fibers reacted with a cross-linking agent selected from the group consisting of DMDHU, DMDHEU, DMU, DHEU, DMEU, and DMeDHEU. Tissue products and webs produced in this manner generally have improved sheet bulk, without losses in strength, compared to similar tissue products produced without cross-linked cellulosic fibers. As such the tissue products of the present invention generally have a basis weight from about 10 to about 50 gsm, a sheet bulk greater from about 8.0 to about 12.0 cc/g and geometric mean tensile from about 730 to about 1,500 g/3".